Bromine trifluoride treatment of halohydrocarbons



it: 5 annumiosmcmz may y y 1 nnoiumn TBIFLUORIDE TnEA'rornNroF l 1 t a Eu-1'1.McBeqLnFnyette;lndnvincentvumnd mu,,comcob Conm,andWaido B.Ligettr Berkley, ail ll lnors :toPnrdueiJResearch tzi; Fayette, Ind., a corporation of Nonsense Thi inventionrelates to a process for theprepof: our invention: is the employment of bromine aretion or fluorine-containing;haiohydrocarbons -trifluoride-to1-producenfluorine-containing high and halocarbons. More;speciflcailmthisinvem molecular weight halohydrocarbons andhaiocarl; tion pertains to th treatment ot:lxalohydrocarbons. especiallembodiment 'bf our invention ,bons with bromine trifluorlde. 1

pr pa iont 5 resides in the reaction of bromine trifluorideand The fluorinating agent in our invention i. e., u i a halohydrocarbon to nproduce high"molecular bromine trifluoride a has long been available to weight fluorine-containing haiohydrocarboris and any investigator of fluorinevchemistry. 1 Itmayj v t halocarbons containing the same number of cari be prepared bypassing elemental fluorineiinto bonatoms as the haiohydrocarbon reacted in the bromine in acoppfir vessel orother container re- IOprocess. The: provision of a method whereby l sistant to the action ot the said reactants wata i theyaboveimprovementsmay be accomplished is temperature of about ten degrees; centigradewunincluded among theaobjects of our invention. tilno further quantityot fluorine isobsorbed, u Wehavetaisoyfound that bromine trifluoride No; limiting difliculties areiencountered :in its thaswexceptional utility in the wfollcvwing ways,

i ailheretofore unreported:

An undesirableanti definitelyfliniitingr characor (DwBromine trifluoride adds fluorine toboints ,teristic of thisiurning1 liquid, however, is its exof unsaturation in an unsaturated halohydrocar- ;jcessivereactivity with most organic matter; {The bony Some brominemay also enter the molecule, fact that this.yliquid reacts yigorously, :when in it for examplewbyadditiontoa double bond, but ycontact lwith most organic material, has proven uthepossible addition of bromine is notto becon- ]a. 1 tremendous obstacle to investigators of the it sidered' an undesirable effect of thebrominetritheir-1. Owingtoithevioient and explosive anature' t fluorid fiu n t p ss- Thuspin the treatof mostreactions;betweentbromine trifluorideandp ment ofaromatichalohydrocarbonswith bromine (organic matter; few successful experiments have t i d r W h ve fo nd any brominegwhich t] been reported. y Nutting (U:S4;Patent1,961,622, is introduced $0 3128 replaceable, with fluorine, fby 1934 June 5) succeeded in reacting brominetrireaction with antimony pentafluoride, if such fluoride and carbon Mttl'flbhlOlidGWtO Qproduce isdesired. -1g l t a;fiuorinatedmethanes,butwexcludingithis bromine-t two-Bromine. triflu ride may be usewtoJ're trifluoride treatmentof zmonocarbonhalocarbons, 1 pl enwit 'fluorine, other halogen atoms in" either nothing has been known regardingtthe'iutility'of 3o aniaromatic, alicyclic; or aliphaticchalohydrocarbromine triiiuoride as a fluorinatinsasent. hen. Intthisirespectwwe haveioundthat the Considerable dimeultyfnot bresent in the treatpresence of; hydrogen has no prohibitiveeflfect mentor carbon tetrachloride, isencountered inn POiIwth i pl fl Iwi H Q OI Dther 1 theIfiuorination, of,haiohydrocarbons.;;;1 Apparent- .whaiogen atoms-inrthemoleculen :1

n 1y] becai se of the hydrogen present, rfluorineting 1 1 t; (3) Bromine tri'fiuoride sreplaces, withfluorine, agen capabieoi reaction with gmonocarbon aiihydrogen: in" halohydrocarbons;: In this respect a; d t e 1 t phatio haiocarbons haye proven themseives :unbFOl'l'iiIiBctliflllOIide Chas been: r'found to have reactionsl i with jqhalohydrocarbons s specific utilityuin ,theEpreparatiomof halocarb'o'ns,

One major obstacle qin the satisfactory fluorina- 1 1beingjinpsomeinstances capable of removing the tion of polycarbon halohydrocarbons rhastbeen 4018.51 l'iydrogeni omsin a 'molecule without austhe concurrent; fission j of carbon-carbon: aiinkages ing substantial: :fission 0t ath'e molecule. 1 '1;

the organic product obtained fromzta reaction with hi among-the objects otouriinvention the provision n ost halohydro'oarbons consists 5 almost: entirely of a ;:;process whereby: i( 1:) bromine1 trifluoride t o! -lca.rbon tetrafluoride and'igothert fluorinated ':maybeusedetoaddsfiuorine to points 'of 'unsaturawreak-down productsLMIfhe search: ;-for:vnew;-.and gytionwoft an unsaturated: halohydrocarboni (2) Inivieww cof; the above disclosures, we nciiide useful,fluorinatingiagents; whichwhavexarlessixde bromine trifluoridemayrbemusedzto:replace, with g terioratingti effect; .upon thegmompound ibeingv; tflnorin henihalogenr-atomsaina halohydrocariiuorinated, hasgabeen extensivelyuconducted; rbomwanqi in bromine .strifluorideu maymbe- Oixririventionithusconcernswitselfiawithha proc- -to replace; twithu-fluorine; hydrogenf atom whereby g halohydrocarbons miay tl be sxtreated halohydrocarbon. t bromine.latrifluoridew-and whereby e tmny liInwsomeyxcases;inewa' andtusefui haiohydrdcaranroduce :various. iorgan-icacompoundsn in eachrin- @tbons and qhailocarbo'ns are "procurdid-irectlyi from stance containing more fluorine than the start the process. In other instances, the dehalogenaused' in; haiohydrocarbon. A preferred embodiment tion or cyclic halocarbons, prepared by the covered.

preparation of useful aromatic or otherwise unsaturated cyclic fluorocarbons and halocarbons. Other obi ects of the invention will become apparent hereinafter.

The present invention essentially comprises the treatment of a halohydrocarbon with bromine triiiuoride at a temperature between about zero degrees and about 175 degrees centigrade, preferably within the lower temperature ranges. The reaction is preferably carried out by admixing the reactants at a relatively low' temperature, e. g., between zero and sixty degrees centigrade, and thereafter heating the reaction mixture to a relatively higher temperature, e. g., sixty to 200 de rees centigrade. The pressure under which the reaction is conducted may be subatmospheric, atmospheric, or superatmospheric.

While the present invention, in its broader sense, is applicable to any halohydrocarbon, a preferred method of operation under the invention involves its application to a hydrocarbon having at least about one-fourth of its original hydrogen atoms replaced with halogen atoms. The halogen atoms may be bromine, chlorine, fluorine,

or iodine, or combinations of several or all mem-.

bers of the class. The process herein disclosed is moreover of still greater efliciency when applied to a hydrocarbon having one-half or more of its original hydrogen atoms replaced by halogen atoms. These halogenated compounds usually allow a more easily controllable reaction, and the obviation of excessively tedious reaction procedure lends pronounced advantages to this preferred embodiment over the same process when employed with halohydrocarbons having a lesser halogen content.

, In the practice of our invention, the halohydrocarbon and bromine tritluoride may be contacted in any suitable manner. Thus, we may place the halohydrocarbon in a suitable reaction container and add the bromine trifluoride thereto. It is sometimes more advantageous to apply the: reverse procedure, adding the halohydrocarbon to bromine trifluoride. Occasionally, it is of assistance to employ a liquid medium for the reaction, e. g., liquid bromine, although the halohydrocarbon or mixture of halohydrocarbons and bromine trifluoride may be reacted directly. A After the reactants have been admixed, with suitable precautions as outlined below, the mixture is heated to a higher temperature, e. g., room temperature to about 175 degrees centigrade, and maintained at this temperature for a considerable interval, for example, three to thirty hours. Any 'excess bromine trifluoride may then be destroyed by the addition of a suitable agent, e. g., cracked 4 considerably wider scope have been employed with success, e. g., the reaction proceeds satisfactorily between zero and 200 degrees centigrade, preferably between zero and 175 degrees centigrade, with slightly more decomposition at the upper temperature levels.

A primary consideration in carrying out the.

process, regardless of the procedure according to which the reactants are contacted, is the prevention of accumulation of unreacted starting material. For this reason we employ constant agitation of the reactionmixture and introduce the one reactant, which is selected for addition, in a portionwise manner, especially during the early stages of the reaction. For this reason, also, we

flnd that cooling of the reaction mixture to low temperatures, e. g., zero degrees centigrade, and subsequent heating of the reaction at a higher temperature, e. g., 100 degrees centigrade, before and after each addition, respectively, is sometimes of particular advantage in causing the reactant in each addition, especially the first additions, to react completely with the other reactant, thus circumventing undesirable accumulation with its contingent pyrolysis or explosion. After the reaction has proceeded for some time, it is usually permissible to increase the rate of addition of reactants because of the diluent effect of the bromine and the iiuorinated product. The reaction may also sometimes be advantageously conducted in the presence of one or more of the products-of the reaction, which in such instances serve as a diluent. However, in no case was omission of the above precautions found advisable: either for the procurement of satisfactory products or maximum safety of the operator.

The reaction vessel may be a nickel tube of considerable diameter and appreciable length, for

. found advantageous not to seal the tube at the ice, cold water, sodium bicarbonate, et cetera,

-Although the above conditions reprment the example 5.2 and 50 centimeters, respectively, sealed at one end. Such a tube, or one similar, proved satisfactory in conducting many of the illustrative examples herein. The means of agitation was, in most cases, a propeller-stirrer,

consisting of a motor-driven nickel rod with four nickel blades appended thereto. which was inserted through the top of the tube. It was also top, in the event unexpected violence manifested itself during the reaction.

The following examples are given to illustrate the practice of our invention, but are in no way to be construed as limiting.

Example 1.Benzot,rifluoride Benzotrifluoride (10 milliliters) was placed in a small nickel tube closed atone end and cooled to zero degrees centigrade. Bromine trifluoride was added slowly to the nickel reaction tube, with constant stirring. After each addition of bromine trifluoride, the reaction mixture was heated to degrees centigrade, maintained at this temperature for two hours, and cooled to zero degrees centigrade. Seventy-six grams of benzotrifluoride and 1'75 grams of bromine trifluoride were added in a portionwise manner to the quantities" originally reacted, with constant agi-' tatio'n. The reaction was then heated at 90 degrees centigrade overnight. When washed with sodium bicarbonate, the organic product separated into two layers, one of which became solid as excess bromine was expelled. This solid product was dissolved in hot alcohol, and water was added to the solution to cause its precipitation therefrom. After standing for eight hours,

optimum for our process, temperature ranges of Tl a yellow liquid was separated, washed twice with *siiedientsiia t a methylcyclohexaneiaii This organi nmmvtiandbdried: over ,Drierite. The product liweithed, .J-fiflzig iarnsaand :contained, by analysis,

tamidtlnemicentti:fluorinenand 24.3 percent other halogen. a

placed n nickel tube, cooled to zero degrees centigrade, and bromine trifluoride added droplse t constant agitation. A-consid- W cess o bromineatrifluoride was used in men ad been and and subsequent cooling d reeseicentigradai the reaction was i1ilzdegrees :centigrade. Twenty hours lowed toisxscom pletes reaction of the in-' excess, bromine trifluoride. was destroyed. with bicarbonate solution. Fifty-one. ghanisisoi; .lvisousnliquid, having an approximate density of 2.5, was separated. Anal- "xsis tofitli :prodiict bowed it to be a halodi- ,fluoriney and 39:69:;pe at other halogen.

mtmheriabo ez l iiigi'a-m or fluorine-containing product lwasi'rtutthemreacted with bromine trifluoride. A similar procedure was employed, the neactiombeingrcarried out at a higher tempera- .ctureezandmantadditional" 25 grams of bromine -trlfludridefbeingdised i action was discontinued a 'fter hours at 165 decei'itigi'ade and th reaction product was urposes as above. A

colorless liquid weighing the analysis df which indicated it to be a mixture ofiuliiilodimethylcyclolieiianes with 'a fluorine content of 41.6 per cent and other halogen conte of .7"-" t W i ;rteen1;gramsi of nonafiuoromesitylene was a nnickelicicontainer and cooled to zero 5 centigrade. In a dropwise manner, 33 grams of bromine trifiuoride was added to the 11984.!51! oni'withiconstant stirring. The rewas; heatedlto 100 degrees centigrade and maintained at this temperature for twelvehour ter lfdestroying excess bromine trifluoridejygi dilute,,,sodium bicarbonate, extit e iig witli hot 'alcaholfwashing, and drying over Drierite, ry viscous liquid was obtained. uct contained 46.9 per cent fluori'iieiiind pe t other halogen.

. j Example 4.Trichlorobis (trifluoromethz l) benzene) One hundred and thirty-five grams of trichlorobis(trifluoromethyl)benzene was placed in a nickel tube, 5.2 centimeters in diameter and 50 centimeters in length, cooled to ice temperature, and 233, grams of bromine trifluoride was added thereto over a period of four hours. The tube was heated to 100 degrees centrigrade after the addition of each major. portion of bromine triof hexafluoroxylene was histztemperature, and the organic ,pxzoduct 1w. SithGIIiIW3ShB(i Vi/ith water after the 6 Two hundred grams separated and found. to be a' mixture of partially halogenated bis(trifiuoromethyl) cyclohexanes and .perha1obis(trifluoromethy1) cyclohexanes.

containing,41.9 per cent fluorine and 24.1 pol cent other halogen.

Example 5.--Halowaz Halowax, a mixture of penta-and hexachloronaphthalenes, was recrystallized from a carbon tetrachloride-methanol solution and treated in a manner similar to that of Example 4. Six

hundred and fifteen grams ;(4.5 moles) of brothe treatment. The re- 455 grams resulted.

fluoride and returned to zero after reaction was complete, as evidenced by no further evolution of bromine fumes from the reaction. mixture. When all the reactants had been added, the tube was heated at 100 degrees centigrade for three hours, at the end of which time excess bromine trifluoride was destroyed with water. The product was then washed with dilute alkali and water.

mine trifluoride was placed in the nickel tube described in Example 4, cooled to ice temperature. and the purified Halowax added thereto with continuous stirring. The Halowax was added slowlyin a portionwise manner over a four-hour CioBrsclsFn.

' Example 6.--Nonachlorohept ane A chlorinated heptane, CvClsHv, was reacted with bromine triiluoride in the manner abovedescribed for J-Ialowax. One hundred ninetyfour grams ofth'e nonachloroheptane was treated with 264 grams of bromine trifluoride and heated at 160 degrees centigrade for six hours. The organic product was obtained by washing with dilute alkali and water, and drying over Drierite. This product weighed 162 grams and was a mixture of heptanes containing 29.8 per cent fluorine and 52.6 per cent halogen other than fluorine.

Example 7.--Pentachloroheptane Pentachlorohepta-ne was treated with bromine trifluoride as previously described for other halohydrocarbons. One hundredjsixty grams of pen tachloroheptane and 226 grams of bromine trifluoride were used in the process, the heptane being added to bromine trifluoride in a nickel tube. The reaction was heated at 155 degrees centigrade for twelve hours, the excess bromine trifluoride destroyed, and the organic product worked up as in previous examples. The product weighed 143 grams and was a colorless liquid, a mixture of hep- I tanes containing 46.3 per cent fluorine and 32.1 per cent other halogen.

Example 8.--Polychlorohe ptancs Thirty-five grams of chlorinated heptane, containing 12 to 13 chlorine atoms per molecule, was" reacted with 0.5 mole of bromine trifluoride'after the fashion of Example 1. After all the chloris nated heptane had been added, the reaction mixture was heated at 90 degrees overnight. At the end of this time, the organic layer was washed free or bromine. and. dried over Drierite. The

very viscous liquid which resulted was a mixture of halogenated heptanes and contained bromine, chlorine, and fluorine.

This bromoclilorofluoroheptane was treated of organic material was again with bromine trifluoride. The mixture: was heated between 115 and 120 degrees centigrade for thirty hours. The resulting organic product was washed free of bromine. Analyses showed the product to contain 34.0 per cent fluorine and 48.9 per cent halogen other than fluorine, with little or no bromine present. This-corresponds approximately to CaClrFr, which has 48 per cent chlorine and 34.0 per cent fluorine.

Other halohydrocarbons which may be treated in the process with bromine trifluoride include .trichloroethane, tetrachloroethane, pentachloroethane, dichloroethylene, trichloroethylene, tetrachloropropane, pentachloropropane, hexachloropropane, heptachloropropane, tetrachloropropene, pentachioropropene, pentachlorobutane, hexachlorobutane, heptachlorobutane, octachlorobutane, tetrachlorobutene, pentachlorobutene, hexachlorobutene, heptachlorobutene, pentachlorobutadiene, tetrachloroisobutene, pentachloroisobutane, pentachloropentane, tetrachloropentene, hexachloroisopentane, hexachlorohexane. octachlorohexene, decachlorooctane, other similar aliphatic halohydrocarbons; dichlorocyclohexene,

polychlorocyclohexanes, bromochlorocyclohexanes, chlorobenzene, trifluorobenzene, pentachlorobenzene, dichlorohexafluoroxylene, chlorononafluoromesitylene, hexachloromethylnaphthalene, and other similar polychlorinated saturated or unsaturated ring halohydrocarbons, including monoor polyalkyl-substituted derivatives thereof.

nature or the reactant, and dependina up n the time and temperature employed, the amount of fluorine introduced into the molecule may be varied considerably.

Modifications may be made in carrying out the method of our invention, and it is to be understood that we limit ourselves only as defined in the appended claims.

We claim:

a 1. The process for the simultaneous introduction or fluorine and bromine into an unsaturated halohydrocarbon which includes the step of mixing an unsaturated halohydrocarbon with bromine trifluoride, maintaining the reaction at a temperature between about zero degrees and about 200 degrees centigrade, and separating from the reaction product a more highly saturated organic compound having an increased It is to be understood that the treatment of un- I saturated halohydrocarbons with bromine trifluoride may be allowed to proceed to anydesiredl extent. In many cases in a reaction of bromine trifluoride and an unsaturated halohydrocarbon, the addition of fluorine, and possibly some bromine, to the points of unsaturation is the firstv step to occur, with substitution being eflected secondarily. As this is the case, a saturated fluorinecontaining halohydrocarbon is thus the first product of such an unsaturated halohydrocarbonbromine trifluoride reaction. The saturated fluorine-containing halohydrocarbon. after being separated from the reaction mixture, may then be further reacted with bromine trifluoride, yielding a compoundlhaving a still greater fluorine content.

The ratioof fluorine to other halogen in the product will be found to vary with the type of starting material and the halogen content of the halohydrocarbon' reacted in the process. For example, the product from the bromine trifluoride treatment of a chlorinercontaining halohydrocarbon may contain fluorine and chlorine, and possibly some bromine. Thus, according to the fluorine and bromine content, and having the same number of carbon atoms as the starting halohydrocarbon.

2. The process of claim 1, wherein the temperature is maintained below about degrees centigrade.

3. The process of claim 1, wherein the halohydrocarbon and bromine trifluorideare admixed at a temperature below about room temperature, and thereafter heated in admixture with agitation at a temperature below about 200 degrees centigrade.

4. The process of claim 1, wherein the starting unsaturated halohydrocarbon is a hydrocarbon having at least one-fourth of its original hydrogen atoms replaced by halogen.

5. Theprocess of claim 1, wherein the starting unsaturated halohydrocarbon is an unsatu-- REFERENCES orrEn The following references are of record in the file of this patent:

Miller, J. A. C. S" 62, 341-4i1940). Lebeail, Ann. Chim. Phys, 9, 241-61 (1906). 

